Sleep
Any process in which an organism enters and maintains a periodic, readily reversible state of reduced awareness and metabolic activity. Usually accompanied by physical relaxation, the onset of sleep in humans and other mammals is marked by a change i
This article is about sleep in humans. For non-human sleep, see Sleep (non-human) . For other uses, see Sleep (disambiguation) .
"Sleep architecture", "Waking up", "Asleep", and "Slept" redirect here. For other uses, see Waking Up (disambiguation) , Asleep (disambiguation) , and SLEPT analysis.
Sleep is associated with a state of muscle relaxation and reduced perception of environmental stimuli.
Sleep is a naturally recurring state of mind and body characterized by altered consciousness , relatively inhibited sensory activity, inhibition of nearly all
voluntary muscles, and reduced interactions with surroundings. [1] It is distinguished from wakefulness by a decreased ability to react to stimuli, but is more easily reversed than the state of hibernation or of being
comatose . Mammalian sleep occurs in repeating periods, in which the body alternates between two highly distinct modes known as non-REM and REM sleep. REM stands for "rapid eye movement" but involves many other aspects including virtual paralysis of the body.
